Findings that implicate biological mechanisms in the etiology of homosexuality provoke a wide range of reactions concerning their ethical, legal, and policy ramifications. However, the mere fact of biological causation can have no implications which are not true of all behavior, because all behavior is biologically (specifically, neurophysiologically) caused at the most proximate level of explanation. Notwithstanding this conclusion, a particular type of biological causation that is not characteristic of all behavior could, in principle, have ethical, legal, or policy implications. We explore alternative senses in which homosexuality might be considered to be biological, including“innate”and“immutable,”and show that“innate”explanations, at least, have some limited (though important) policy implications. More generally, however, we conclude that inferring ethical, legal, or policy consequences from etiological knowledge is much less straightforward than typically assumed.